(1) Field of the Invention
The present invention relates to temperature control blow molding equipment which can be used in a molding machine capable of successively accomplishing a series of operations from injection molding a parison of a thermoplastic resin to stretch blow for molding a container therefrom and which has both a temperature control mold for the parison and a blow mold.
(2) Description of the Prior Art
U.S. Pat. No. 4,105,391 discloses an injection-molded parison carried to a temperature control position, where a temperature distribution of the parison is adjusted, and the temperature-controlled parison is then delivered to a blow molding position, where it is molded in a blow mold into an article such as a bottle using the stretch blow molding method. Afterward, the molded article is carried to a removal position, where it is removed from a carrying means. This type of molding machine is well known and widely used.
In the above-mentioned known molding machine, there are an injecting operation zone, a temperature control operation zone, a stretch blow operation zone, and a mold release operation zone, and the operation in each zone is carried out as the workpiece is advanced or a carrying means such as a rotary disk. Further, the injecting operation zone requires the longest time interval, while the working periods in the other zones are extremely short. For this reason, the temperature control of the parison is best accomplished by taking the time necessary for the parison injection molding into consideration.
Generally, the time required for the temperature control of the parison and the parison temperature for it are determined on the basis of a temperature of the injection-molded parison, and the temperature of the parison varies even during its conveyance. Therefore, the temperature control of the parison is achieved by taking account of this temperature variation during the delivery. However, in the case of a polypropylene resin, the temperature control of which is more difficult than that of a polyethylene terephthalate resin, repeated observation has been necessary for the decision of a temperature control timing.